The present invention dramatically improves the speed of operation, load-carrying capability, and parasitic power consumption of spindles used in the textile industry for spinning and twisting yarn. This unique spindle comprises hydrostatic, self-lubricating, swing-type bearing pads disposed on a non-rotating shaft containing a lubricating means for introducing a lubricant between a rotating outer sleeve or shell and the bearing pads themselves.
Bearings may be classified broadly into three main categories: hydrodynamic sliding bearings, rolling bearings, and hydrostatic sliding bearings. Each of the aforementioned bearings have problems associated with load-carrying capacity, accuracy, lubricant requirements, friction, wear and fatigue.
Spindles used in the textile industry for spinning and twisting yarn typically employ rolling member bearings, usually ball bearings. Use of such bearings results in textile spindles with limited speed, load, and power capabilities. Furthermore, rolling member bearings are normally grease lubricated causing sealing and product contamination problems.
Rolling member bearings characteristically involve bearing surfaces which are capable of rolling on each other with a lubricant being disposed between the bearing surfaces. Rolling member bearings include inner and outer rings which are spaced apart to define an annular space which receives a plurality of rolling members.
Due to the desire to increase textile production, various attempts have been made to eliminate speed, load and power limitations. One method has made use of a high speed, high precision, low load-carrying spindle. Unfortunately, when these spindles are used to spin or twist heavy spools of yarn, they cause undesirable spindle vibrations and greatly increase power consumption. Elastomeric mounts have been used to dampen displacements caused by those spindle vibrations, however, lubricant eventually leaks past the mounts and contaminates the yarn. Thus, these high speed, high precision, low load-carrying spindles result in lubricant leaks, spoiled yarn, smaller than optimum spools, slower speeds, larger drive motors, increased air conditioning in the textile plant, and limits on the total number of spindles used per frame.
It is believed that the currently available spindles have been pushed to their upper productivity limits. The present invention provides an improved spindle which permits higher speeds, greater load-carrying capacity, and less power consumption. The spindle of the present invention overcomes the disadvantages of the aforementioned spindles by employing a novel hydrostatic, self-lubricating, swing-type bearing. This hydrostatic, self-lubricating, swing-type bearing provides internal-- dampening and a self-compensating means to allow minimum clearance and lubricant consumption.
One example of a hydrostatic, self-lubricating bearing is disclosed in U.S. Pat. No. 4,035,038 (Hinchcliffe et al), issued July 12, 1977. Hinchcliffe et al relates to rolling machines and, more particularly, to controlled deflection rolls comprising an inner non-rotative shaft having a roll shell journaled about it, the inner shaft having hydrostatic bearings directed against the inner surface of the roll shell.
The shaft according to Hinchcliffe et al contains an arrangement of pistons, the outer end of each comprising a hydrostatic bearing pad which supports the roll shell internally. Each hydrostatic bearing pad is comprised of a toroidally shaped member that is flexible and resilient. Each piston has a channel through which pressurizable fluid, usually oil, may pass into the body of the toroidal member and into the space between the toroid and the inner surface of the roll shell. A pressure drop of the fluid across the piston permits axial adjustment with respect to the piston and the roll shell. The pressurized fluid keeps the toroidal member inflated, and the fluid keeps the area of contact between the toroidal member and the inner surface of the roll shell well lubricated. The pressure drop and axial adjustment of the piston are self-correcting according to the load thereon. The piston design of Hinchcliffe et al is expensive in both mechanical design and lubricant consumption.
Various gas bearing guide rolls are set forth in U.S. Pat. No. 3,753,517 (Takenaka et al), issued Aug. 21, 1973; U.S. Pat. No. 4,030,784 (King et al), issued June 21, 1977; and U.S. Pat. No. 3,645,589 (Bird), issued Feb. 29, 1972.
Takenaka et al provides a guide roll for filaments as used in apparatuses in which the draw-twisting, draw-winding, false twisting or heat treatment of synthetic filaments and the like are carried out. The guide roll includes a fluid bearing, e.g., an air bearing, for high speed operation. A cylindrical roll body of the filament guide roll is rotably fitted to form a clearance between a shaft and the guide roll body. The shaft is provided with an air passage through its axial center for the introduction of the pressurized air, and branching from the air passage is provided in the shaft orifices from whence the pressurized air is introduced to the clearance to form therein an air film by which the roll body is supported about the shaft. This design may be suitable for guiding single filaments, but is unsatisfactory for carrying heavy loads, such as spools of yarn.
King et al relates to a gas supported or gas bearing roll shell assembly in which a roll shell is rotably carried on an axle which has an axial gas feed channel and, in the bearing zone of the roll shell, also has radial openings through which the compressed gas passes in a bearing gap between the axle and the inner wall of the roll shell which are especially useful as thread overrun rolls in textile machinery involving the high speed transport of threads, yarns or the like.
Bird also discloses an externally pressurized gas bearing roll shell which utilizes a permeable sleeve to distribute pressurized gas from a plenum to the load-carrying gas film.
The aforementioned air bearings are used as guide rolls in the twisting of single filaments and would not be capable of maintaining the speed and load-carrying requirements of spindles used for spinning or twisting yarn onto a textile spool. Furthermore, the vibrations caused by using such guide rolls would be disruptive to both the spindle and the textile machine.
The present invention overcomes the many disadvantages of the aforementioned spindles and guide rolls by providing a unique hydrostatic, self-lubricating, swing-type bearing about a non-rotating shaft of a spindle. Yarn contamination can also be avoided by using air as the lubricant in this novel spindle. Furthermore, the swing-type bearing pad design provides internal dampening and a self-compensating means to allow minimum clearance and lubricant consumption. The present inventors have developed a novel spindle for use in textile spinning, textile twisting, grinding and the like which produces enhanced speed and load-carrying capabilities. Also, by locating the bearing surfaces inside of the spool, the cantilevered or moment loads on the currently available bearings are greatly reduced. That is, disposition of the bearing inside of the spool will greatly shift the critical speeds upward.
Additional advantages of the present invention shall become apparent as described below.